The Cozy allows residents stuck in sweltering apartments to regulate the amount of steam heat a radiator emits.

When it comes to housing, New Yorkers face one big, wasteful problem: That strange set of pipes sitting underneath a window emitting banging and gurgling noises. Each frigid winter, countless Big Apple residents deal with a radiator that either doesn’t work or heats the apartment to a temperature and humidity level that’s more appropriate to a Floridian beach.

Most Manhattanites aren’t able to regulate their heat with a thermostat. Instead, pre-war buildings (constructed between 1900 and 1940) are warmed by a system that boils water in the basement and sends hot steam, which rises and warms rooms through a network of pipes. At installation time, these systems worked astonishingly well, facilitating the construction of the city’s upward-piercing skyline. But the introduction of double-paned glass windows and other retrofits changed the temperature needs for various rooms. So today, a landlord has to turn on the boiler for long enough to heat the coldest room (it’s virtually impossible to redirect steam heat), prompting overheated tenants to open their windows to the icy air outside to regulate the temperature.

Radiator Labs, a startup in downtown Brooklyn, N.Y., introduced the Cozy to eliminate this waste. The device fully insulates a radiator and pushes out heat via a fan that is wirelessly controlled by a resident’s smartphone or computer app. When the fan is off, the radiator becomes hotter and hotter, and its excess heat eventually diffuses back through the building’s pipes — signaling to the basement’s thermostat that all the rooms have been adequately heated. If Cozy is used building-wide, Radiator Labs reports that it can save up to one third of the energy required for heating.

Marshall Cox, the device’s inventor, lived in a “horribly overheated apartment” while he studied for his doctorate in engineering at Columbia University. He didn’t mind the temperature himself, but his brother, a professional ballet dancer, stayed with him for six months during a Broadway run and complained nonstop. Cox invented the system, essentially, “to shut him up,” he says.

Radiator Labs has already convinced 10 buildings to install the Cozy in every flat. With help from the New York State Energy Research and Development Authority, Cox has plans to expand to 40 buildings. Radiator Labs also sees vast growth potential in other urban cities that were built at the turn of the century, like Chicago or Philadelphia.

“If you want to put a dent in fuel consumption and pollution in big cities,” cutting out inefficiencies in heating — “the single largest energy expenditure” — is the way to go, Cox says. “For the first time in the history of the building,” he adds, “we’re making the tenant comfortable while reaping this benefit for the building owner.”

With the average American shelling out $3,052 on energy costs each year, the Cozy has the potential to provide huge monetary savings for apartment dwellers and immeasurable savings for the planet as well.